How difficult is the CIS to EFI conversion and how expensive ?
 

Is the EFI more straight forward and easier to tune than the CIS?

If I heard right, the CIS is good for about 400 RWHP. What is the HP potential on the EFI? Are the parts easy to come by and at what general cost?

Parts are easy to come by but you will not really know which ones you need until after you bought the wrong ones.

EFI is much easier to tune. You can turn your engine into scrap metal with just a few keystrokes.

EFI always costs $5,000 more than you have already spent. After you are done it will only cost $5,000 to start over and do it again right this time.

Me bitter? Nooo.

Actually, EFI is great but it is no magic pill. You still have to tune your engine. You have to figure out which parts and sensors work correctly for your setup. After-market sensors are not as reliable as OEM sensors. It always costs more than you expect. It will not be as reliable as CIS for a while until you get all the details sorted.

With regards to tuning either systems...leave it to the experts with the proper equipment. Too lean for only a few seconds and you're doing a rebuild.

The potential for an EFI system is totally dependent on so many other variables (exhaust system, turbo, cams, heads, fuel injectors, etc.). The EFI system relieves the mechanical limitations of the CIS system, and allows for precise delivery of fuel, and if you also have crank fire ignition, a more accurrate delivery of spark. The only way to take advantage of EFI's potential, is to have all of the components of a system perfectly matched, such that the least efficient device becomes your limitation for HP.

Speaking from experience (I'm right in the midst of my conversion to EFI), the best approach is to determine a budget and a desired HP. Than you can enlist the help of both a professional builder, and tuner in order to determine what modifications will be necessary in order to achieve your goal, and from the parts list alone, determine if you are within budget alone. Cost aside, your best choice would be to enroll the services of the professionals to take care of all of the details and trials and tribulations. This board is full of professionals in the industry and DYIers that can assist in supplying an endless amount of information and experience. The purchase cost of the EFI system ($3k to $10k) is the cheapest part of the conversion. The first issue is, whether you're do for a bottom-end rebuild or not, replacement of your rod bolts (which are limited to 450HP at the crank), followed by upgrading the "other" HP limiting items mentioned above in order to achieve your HP goal. Assuming that you can do all the mechanical work yourself, you'll still need to take your car to a tuner that is expert with the EFI system you installed. Since I'm currently still on that slippery slope, I can definitely say that you shouldn't even ponder going EFI unless you have a bare-bone budget of at least $10k. Will you meet your budget, no way. If for no other reason, you'll run into at least one "while you're in there you might as well...".

Good luck on your decision,
David
186 911 Turbo

I spent over $10K for EFI parts, but I think you could build a good system for half that. Figure another $1K for dyno tuning. If you want to do it yourself, I recommend finding a very experienced tuner first and either buy the parts from him or buy what he recommends. After you have the parts installed and the car running well enough to drive it, take it to the tuner to do the rest. I am surprised there aren't "good" EFI kits available for 911/930's.

I'll second that http://www.pelicanparts.com/support/smileys/wat6.gif

Ummm... Maybe $1000 to get a good WOT baseline, but not drivability (hot start, cold start, idle, altitude, IAT correction, ECT corrections, etc.).

Man! This is an eye opener. I thought there would have been a 'formula' so to speak - some guide to follow by now or perhaps an aftermarket bolt on kit, but it looks more like black magic from what I am hearing.

The reason I asked is, I am trying to determine what the next step of performance is beyond headers, cams, an intake and dropping weight? EFI sounds much more costly than I imagined.

I think Imagine Auto developed a kit using the pancake manifold.

The problem with EFI is the "while you're in there syndrome". As someone mentioned above- the entire setup is only as good as it's weakest link.

You can waste a lot of money in the process, so think everything through before you do it. I blew a bunch of money balancing and Extrude Hone-ing parts that I didn't even end up using.

Usually, people who convert to EFI want power in the higher end of the spectrum (500+hp). If this is the case with you, then you will have to beef up the internals of your engine (balance all reciprocating parts, upgrade the connecting rods, ARP studs, etc) that all costs a good chunk of money.

IMO if you don't want big power, I don't see the point in going EFI- there are lots of good components on the market that allow for darn good CIS engines. I have spent about $20K in just parts for my EFI build. Now that includes an upgraded turbo and I/C, headers and muffler and other things that aren't directly related to EFI per se, but like I said, if your going for big power, it's not just a matter of bolting stuff on and lighting the candle. It's a pretty complex process as I have come to find.

Measure twice and cut once kimosabe.

If you do an exhaustive search on EFI for the 930 you will find the actual "need" only occurs if you wish to go past 400RWHP.
At that point your costs skyrocket.
If your goals do not include exceeding that boundry (by much) there is no significant advantage to EFI over CIS.
There are 930 EFI kits for sale by tuners. They start at about $7000 but I would expect to pay more than that before it is all done.

Here is my expirence with EFI.

I went with EFI cause I was running lean with CIS. I hated CIS and Porsche should have be ashamed to use it when VW was using EFI in the early 70's. Rant over.

EFI was the hardest thing I ever did to cars. I am not a computer guy. I did everything myself so it was really hard for me. EFI is also the coolest thing for cars since they were invented.

I paid $4k for EFI parts plus $2k for other hardware parts. ie intercooler and plumbing etc.

If you pay someone to do it for you, then EFI is easier. If you do it yourself then it is harder.

On second thought that's true, my tuner said he usually charges $750 for a basic tune. I'm up to $950 and still not done and I think he's been generous with his unbilled time.

Well, I'll add a different perspective...
Yes, EFI is not easy; particularly if you expect turn-key, run like a dream out of the gate. But, in my case, I used an "open-source" ECU, I did A LOT of research, spend A LOT of time making it work, and so far had been tuning it 100% by me WITHOUT dyno (yes - I'll get there by end of summer).
Its been a long road. Its not exactly smooth. But, my car is used on the track most of the time, but I also drive to/from the track, so I also need to have good-ehough driveability.
I don't know how mine compares, but she runs well now; after 15 months since rebuild & EFI change. And I'd do it again if I have to. And parts probably cost me <$5K.

Well, thanks for the input. It looks like for my budget I am going to be limited to the 400 hp mark. Actually, 400 horsepower isn't all that bad .... it will kick butt on 90% of the cars on the street, and considering the 930 hooks up and launches so well, it will beat many cars with more HP.

After having spent the last three years making my EFI project work, I would have to say I would have been a lot better off selling the 79, taking the cash I spent on the EFI and bought a newer model. And for the money I spent, I could have bought a nice late-model. On the other hand, I am a die-hard DIY person and enjoyed designing it, working on it, and tuning it. One other comment - I could have never paid someone else to do the work I've done - it would have been far too expensive, even with the problems I've had along the way. And unlike some, I think CIS is very capable on these cars, even modified.

If I had known how long it would have taken and how much it would cost, I would have bought a 997 turbo or GT3. I like my car and it is really fast but no car is worth the trouble I went through to get to this point.

You would be AMAIZED at what properly set up CIS 400RWHP 930 will whoop up on. How about a brand new Z06 or Viper?
Full boost before 2600rpm, 22+mpg, and perfect A/F ratios are all possible while still using CIS. There are many threads on tuning and modification of CIS if you are interested in going that route. The down side (maybe) is that you are best to do the tuning yourself with an LM-1. You need to be one with your engine. Zin and the CIS. ;)

Brian you are delusional, I love you man but a 400 hp car on CIS is not healthy for a long time and further, no way you are getting 22mpg I am getting tired of conjecture, black magic etc post the bloody data that supports your claims until then unless you need more 930 parts please simmer down. On CIS my car an 87 930 3.4 made 379 rwhp and 368ftlbs of torque, a pretty square engine. The mods included B & B headers, exhaust, Ruf hybrid Turbo, Andial intercooler, Andial SC cams, stock bottom end, stock wastegate with a boost controller (dial a death) C02 was set a 3% and the thing ran pig rich spewing unburnt gas everywhere. Sorry Brian not trying to flame anyone I am only interested in seeing some empirical data to support your claims.

I think you just proved RARLY8's point. You haven't touched the heads which can bring some serious gains, you are running "pig rich" as you stated, running an early turbocharger and you are within 21HP of Rarly8's claims. As far as mileage goes, I suppose 22MPG is very doable with a weight reduction and R&P gear optimization, but at this point, who cares? With over 470 HP at the crank, you're are not in the same league as the Prius's of the world. :D

He is FAR from delusional - I expect he simply knows how to properly set up and tune a motor. Getting a CIS car to have good A/F ratios throught the rpm range is not black magic, it's actually pretty simple. Real Porsche 'experts' have been adjusting the 'non-adjustable' WUR for over 30 years - it really baffles me that the aftermarket tuners can't handle this task so instead they sell bigger fuel heads and 15K EFI conversions....

I understand your skepticism and I don't take it personally.

The "crazy talk" about mileage, elimination of lag, and A/F ratios has come at great expense and time from many people. I don't claim to have created any of this myself, it is an accumulation of knowledge from several sources. Most, if not all of those sources will not tell you how it is done. Why? Because they make HUGE bucks selling and tuning EFI. An adjustable WUR only costs about $300.

That being said, I am not an EFI hater. You just need to know what your options are before spending the money. I would be livid is somebody told me after spending $10K on EFI that I could have spent $300 for similar results.

Remember, power and CIS are two different entities. You have to build the engine to make power using CIS compatible components, THEN tune the CIS to optimize it.

All of this banter is pointless if you don't like or don't want to learn and work on CIS. There is no option with CIS but to do it yourself. Folks like Brian Leask will help you but ultimately you are the one doing the tuning.

Oh I forgot I had some head work done, euro fuel lines and fuel distributor and yes I could make 400+ at 1.1-1.2 bar but the engine would go from fat tune to lean over the rev range. I spent a tonof money on Motec as did David and it is not a panacea we both ran into problems, albeit exceedingly more drivable across the rev range. I will hopefully be posting my numbers on Monday, the good thing is I benchmarked the engine before the conversion as well. Do a search on Olli on rennlist forhis astounding numbers.

My car had some head work, the manifold extrude honed, "real" headers (not GHL, etc), euro lines, tuned WUR (by me) to give a flat AF curve, fuel head mod (probably not needed), a STOCK airbox, a Kokeln turbo and IC, matched injectors, 964 cams and I'm sure something else I can't think of. It put out consistent 420 RWHP (and 390 ftlbs) at one bar. When I tore the motor apart (to go to EFI), it was in pretty good shape. One last point - it idled perfectly, started every time and could be driven daily.

As a side note, I spent almost 3 hours and 100 miles street tuning my EFI system today. I enjoyed the hell out of it because its running incredibly well, but I'm not quite happy with the results yet. Sure, WOT is fine - whoopee - most people can tune that. But add 85 degree ambient, heavy traffic, 85 mph freeway, then stop and go, cold start, hot start, idle, ignition timing, 4 gears and so on, all on an air-cooled, turbo-charged, rear mounted 1979 technology motor - this is not easy. Oh yah, add boost to the process at varying RPM and you'll get an idea of how tricky EFI really is.

A good running CIS car is not so bad.

Sorry for the hijack.

If I had the EFI project to do over, I'd probably do the same thing just because I'm a hardcore DIY'r and this was just the next in a procession of bike and car projects. Do I wonder now if I should have just bought a used 996TT? Sure, but that can be another project. I can't imagine not looking forward to the next project. The problem is I can't see getting rid of this car so I'm going to need more garage space and of course more money :D.

Schnele - you know you're right, it's easy for me to make these great claims when I don't have to back them up. I consider myself an honest person so I figure you should take my word for it. Well this is the internet and you shouldn't just blindly accept things.

You could write a book on tuning and modifying CIS just like the many books written about EFI. It is a moot point now but I'm sure something could have been done to fix your CIS problem. More and more folks are starting to surface with 400+RWHP CIS 930s with good A/F ratios to redline. Not a lot of those guys are interested in reducing lag or increasing fuel mileage so they don't go the extra mile.

The only measurements that truely matter are the A/F readings. Several folks have posted those. I think Craig did most recently. You can also see boost threshold on a dyno sheet. Mileage is a little tricky. The best data for that comes off of a GPS sense odometers are sometimes optimistic.

Digressions asside, the riginal posting inquired how difficult and how expensive is it to convert CIS to EFI. The simple answer is it is not that mechanically difficult. The tuning is the difficult part. It is expensive. Even if you did all the mechanical work and tuning yourself it would cost several thousand dollars. There are alternatives such as MegaSquirt that allow you to go as far as building the actual computer boards yourself. At that point it becomes a time thing.

Especially when you shave tons of weight from your car.... It actually becomes quite a rocket!! Mine was very quick before I spun the rod bearings!!

i think sand man had his in the 20's on gas milage and upper 400 hp with cis and and adjustable wur with the speed switch

I'm not buying the 20mpg with any fuel system. Maybe downhill with a tailwind. I'm still getting about 10 mpg with EFI, although I've never driven the car without getting into the boost.

20+mpg is obtainable on the highway off boost. The moment you get into boost it's all over. I get about 5-7mpg on the track, about 12-15mpg in town (some boost ;)) and 20+mpg on the highway with my low gearing. If I had a taller 5th gear it would be even better.

That is what I decided. Until you rebuild the engine for 50 or 100 more horsepower, EFI is a big waste of time and money because you will end up with no more than a maximum of 5-10% extra power (which is the outside limit that fine tuning your timing advance achieves). That is assuming you tune it perfectly.

People don't often mention that an EFI system needs to be tuned for all kinds of parameters, such as the coldest day of the year and the hottest day of the year and everything in between. Your EFI might work great at the dyno, and then need several months of real world driving to really fine tune perfectly.

If you can make sure your CIS is dumping enough gas to keep your AFR at 12.2, you will be okay.

EFI is essentially optimizing the timing and tweaking the amount of fuel on the set up you already have in place. You could add EFI now and decide to go with a different manifold and everything else when you actually rebuild the engine down the road and you will need to redo your EFI......That is a waste.

If you want down and dirty performance, drop your tranny and redo your gears. Lower 4th a lot, and lower 3rd a little. Or just lower whatever gears you have trouble shifting into on the boost, in other words, whichever gears you are finding yourself out of the power band when you shift to them. No more expensive than an EFI kit, and you end up with a new tranny.

For CIS, imagine auto is coming out with a fully programable system, and they already have a fuel head to deliver more fuel if you are running lean. That will be worth checking into.

I agree with most of the folks here that EFI really isn't worth the added expense over CIS, but if you love working on engines it's the cat's meow :). It's so cool to be able to bring up data or make fuel and ignition changes with a keystroke.

As Don mentioned, it's a bear to get it balanced for on/off boost, cold start, part throttle, etc. But when it works, it's like magic. My tuner finished most of the dyno tuning on Friday and I've been tuning from data logging since then and now it's running great. I still have to do more tuning especially while someone's driving, but I sure like it so far.

I just checked and my mileage over the last few days has been 12.5 mpg and that includes quite a bit of dyno time. I've also found some very rich area when cruising at part throttle, so there's better mileage to come.

I strongly disagree. EFI puts the 930 in a different class of sportscar. It almost erases the 30+ years that have gone by since the 930 was designed. EFI enables you to take a 300 hp 80's car and transform it into a 600+ hp semi modern car.

I have 505 rwhp at .85 bar and have more tuning to do. I imagine I could get 600 rwhp out of this car with a few more changes (intercooler, tuning, ...).

I do agree that EFI is not necessary. I'll even agree that it is not financially worthwhile for street cars. However, don't get the wrong idea about it's capabilities. It can really transform these cars.

Here is another perspective. Try beating a Z06 on the track with your best CIS 930 and you are very likely to be disappointed. But with EFI you will rule the track.

DISCLAIMER: When I mention EFI in this posting I am assuming all the normal upgrades as well (turbo, intercooler, heads, intake, headers, ...) This is part of the "while you are in there" effect.

What I said was that EFI is a waste of time to put in now if you are going to do your horsepower engine mods later on. In other words, putting the cart before the horse.

CIS is fine for a mild engine, and when you add the 100 extra horespower and know what your plan is, then you add EFI according to what manifold you will use and what your fuel needs are instead of doing an EFI conversion twice, when you don't have a lot to gain in horsepower from EFI on your stock engine.

No one is going to suggest that EFI on a 500 hp car is optional, but on a stock 82 with a aftermarket exhaust and k-27, you don't need EFI before your eventual rebuild. And you may end up buying new EFI fuel injector parts if you change things inside your engine or go to a 3.2 manifold, and you will need to tune it again. So why not wait?

You will gain a LOT more with 7 or 8 grand on a stock engine by doing other things first, like weight reduction and lowered highway gears. A 10% weight reduction is MUCH MUCH better than a 10% power increase, and changing gears is like adding 50 horsepower.

I have Schnele's CIS system on my engine now, I have SC heads, 3.3 pistons and cylinders, built on a 79 SC 3.0 engine so there are some differences. I have also plumbed in a 7th injector that I can adjust to fire
on any given boost pressure and a MSD BTM retard ignition and twinplug.
I hope I have better luck than Lincoln at getting it to run well through the entire RPM band. I am not out to meet any horsepower numbers so thats not a concern, as I am not trying to have the fastest car on the road, but if I am anywhere close to 400hp in my 914 that puts me around 5lbs per hp which aint to bad.
I plan on breaking the engine in on the dyno and tune from there, if things go well the next few weeks getting it all back together I should have some results within a month.

Kirk - a typical laggy 930 will have a difficult time with a torque monster Z06 on the track. The type of engine building and tuning I have described is not typical and will result in a CIS 930 that can handle a Z06 on the track. Would you like to come down to Huntsville and see some firsthand proof that it can be done? Shoot me an e-mail and we'll set it up. The only catch is you have to take me for a ride in your beast!

If you are looking at comparing peak HP between the CIS and EFI, you are missing most of the value of EFI. And in my opinion, most chassis dyno's are crap for providing "real" comparative HP, but OK - you have to start somewhere. There were three things my conversion improved - throttle response, application and improvement of torque, and HP. Even if I did not gain a single additional HP, the throttle response and quicker torque would put me in front of any CIS car. A CIS car requires that the metering plate move before fuel is added which takes significant time (relatively speaking) and the ignition timing operates in a very narrow window. With EFI, it adds additional fuel measured in milliseconds and is completely adjustable. Couple this with the ability to advance the ignition (anywhere) and its see ya later CIS. So, my point is, don't consider EFI just because you want more HP. I gained less than 100 extra HP, but it drives like a completely different car now.

With all this being said, I still really like CIS.

Don - you are assuming that the CIS ignition is left stock. You can eleminate a lot of evils by getting inside the dizzy. Also while the intake plumbing of the CIS designs in a spongy throttle it is made much worse by turbo lag and other issues. When you take away these issues CIS and EFI come closer together.

EFI will always be quicker and more precise but there comes a point where it is not so markedly significant.

Kirk has contacted me and we are arranging to get together. You have my impressions as a defender of CIS. It's a hard sell but I think Kirk will appreciate the capabilities of a well set up CIS turbo.

If you're getting 20 mpg in any 930 then you're not driving it right. :)

+1

Ha! You're right about that!

I think there is a place solid and completely valid argument for both. CIS is proven, it modifies well up to a certain point and is fairly simple. EFI is proven, can handle any engine config, but is far from simple. I like them both but for different reasons.